The key is to see what happens and if it is what you expected. Can this also be emulated in any version of Windows to verify this is what happens there?
I hope that clicking listview header and then bumping message to the application happens in any Windows version. I hope.
Anyway, I do understand WHAT I have to do pretty well. What I do not understand well is HOW I do that. You know, you may understand the language, but thats not enough to speak in it. Especially not patching something, but writing something from scratch (as with test).
I've stated many times that I am not C programmer (though programming is my job, but I do web stuff). And the only reason why I started patching wine is that several very important for me bugs were not fixed for quite long, so I started digging into it.
But I've looked through listview tests and it seems to be quite simple (much simplier than WinAPI and C appeared to me at the very start :) ), so I hope to figure it out.